1. Field of the Invention
The present invention concerns a transmission antenna for magnetic resonance applications of the type having a basic configuration known as a “birdcage” antenna.
2. Description of the Prior Art
In magnetic resonance imaging, transmission and reception antennas separated from one another are used, in particular in the head area. The antennas are typically also designated as coils. Among other things, the requirement to design the transmission antennas to be detunable results due to the use of separate transmission and reception antennas.
In the prior art, transmission antennas are normally fashioned as birdcage resonators. They therefore always have two ferrules as terminating elements, wherein the ferrules are fashioned identically. In particular, the ferrules are composed of ferrule segments that are coupled with one another via ferrule capacitors. In individual cases, antennas known as TEM resonators are used as an alternative to birdcage resonators.
The transmission antennas known in the prior art operate quite well given symmetrical examination subjects and relatively low static magnetic fields (up to approximately 1.5 Tesla). However, the quality of the radio-frequency transmission field decreases given asymmetrical examination subjects and larger static magnetic fields (for example 3 Tesla and more).